1. Field of the Invention
The present invention relates to a loudspeaker used as audio equipment, in particular to a loudspeaker having an edge at an outer periphery of a diaphragm, wherein an outer end of the edge is attached on an attaching surface which is formed at the inside of an outer peripheral rim of a speaker frame.
The present application claims priority from Japanese Application No. 2001-304862, the disclosure of which is incorporated herein by reference for all purposes.
2. Description of the Related Art
A conventional loudspeaker for reproducing music or the like has a basic structure as shown in FIG. 4. FIG. 4a is a top plan view, and FIG. 4b is a sectional view taken along a line xxe2x80x94x of FIG. 4a. In FIGS. 4a and 4b, a magnetic circuit 1 comprises a magnet 2, a lower plate 3, and an upper plate 4. In the magnetic circuit 1, a gap between magnetic poles is formed between the upper plate 4 and a center pole 5 which stands straight from a center position of the lower plate 3. A coil bobbin 6 which sets a voice coil 7 by winding is located so as to arrange the voice coil 7 within the gap between the magnetic poles. A center cap 8 is mounted upon an upper end of the coil bobbin 6. At the vicinity of the upper end of the coil bobbin 6, a center portion of a diaphragm 9 is fixed. An annular edge 12 is connected with an outer periphery of the diaphragm 9. The diaphragm 9 is attached on an upper portion of a speaker frame 10, which is provided on the upper plate 4, through the edge 12.
On the upper portion of the speaker frame 10 is formed an outer peripheral rim 10a, which has an attaching surface 10b inside it. At the outer end of the edge 12 is formed an outer end portion 12a, which is mounted on the attaching surface 10b as a part of the speaker frame 10. The outer end portion 12a is pressed down onto the attaching surface 10b by a gasket 13, which is also attached onto the attaching surface 10b, so as to be airtightly attached onto the attaching surface 10b. 
In addition, one end of a damper 11 is connected with the coil bobbin 6, and the other end thereof is supported by a damper supporting section 11a, which is connected with the speaker frame 10, so that the voice coil 7 can be accurately held within the gap between the magnetic poles of the magnetic circuit 1.
In such a configured loudspeaker, the coil bobbin 6 is oscillated according to driving signals supplied to the voice coil 7. The diaphragm 9, which is supported by the damper 11 and the edge 12 having a function of suspension, is oscillated by the oscillation of the coil bobbin 6, thereby reproducing sound based on sound signals supplied to the voice coil 7.
In the conventional loudspeaker as mentioned above, an attaching screw section 14 for attaching the speaker frame 10 onto a baffle plate or the other housing is formed on the attaching surface 10b of the speaker frame 10. The gasket 13 has a notch 13a which corresponds to the attaching screw section 14. An outer peripheral surface of the gasket 13 is abutted to an inside of the outer peripheral rim 10a of the speaker frame 10, thereby positioning the edge 12 which is fixed by the gasket 13.
According to such a structure of the speaker, a size of the speaker frame 10 can be set by making the best use of a speaker setting area on a baffle plate or the other housing since the attaching screw section 14 is provided inside the outer peripheral rim 10a of the speaker frame 10. However, since the gasket 13 is provided inside the outer peripheral rim 10a of the speaker frame 10 to fix the edge 12, an outer diameter Lxe2x80x2 formed by the edge 12 and the diaphragm 9 is restricted by a width of the gasket 13. As a result, an inside area of the speaker frame 10 can not be effectively utilized as an oscillation area formed by the diaphragm 9 or the like. In other words, since an outputted sound pressure level of the speaker is in the relation of function with the oscillation area, the conventional structure of loudspeaker has any problem that it is difficult to obtain the enough level of the outputted sound pressure which corresponds to the inside area of the speaker frame 10.
Further, since the gasket 13 is used for positioning and fixing the outer end of the edge 12 in this case, the number of parts are increased to cause a cost-up.
The present invention has been proposed in order to settle the above-mentioned problems. An object of the present invention is to provide a loudspeaker which can obtain an enough level of outputted sound pressure by means of effectively utilizing the inside area of the speaker frame as the oscillation area, and which can reduce the number of parts by the non-use of gasket.
According to the first aspect of the present invention, there is provided a loudspeaker comprising an edge at an outer periphery of a diaphragm, in which an outer end portion of the edge is attached upon an attaching surface formed at an inside of an outer peripheral rim of a speaker frame, wherein the outer end portion is formed with a direction to the inside from the outer most periphery of the edge, and has an outer periphery surface which is allowed to abut on the outer peripheral rim of the speaker frame.
According to the second aspect of the present invention, there is provided a speaker including the first aspect, further comprising an attaching screw section of the speaker frame provided on the attaching surface, wherein the outer end portion has a thicker wall portion than a thickness of a screw head of the attaching screw section, and a notch for avoiding the attaching screw section.
According to such a construction, the present invention performs the following function.
According to the first aspect of the present invention, the outer end portion, which is provided at an outer end of the edge, is formed with a direction to the inside from the outer most periphery of the edge, and is attached onto the attaching surface of the speaker frame. Thus, the outer periphery of the edge is allowed to approach the outer peripheral rim of the speaker frame as much as possible, thereby enlarging an outer diameter composed of the diaphragm and the edge to the maximum of the speaker frame. Consequently, the inside area of the speaker frame is effectively utilized as the oscillation area, so that enough level of outputted sound pressure can be secured.
In addition, since the outer peripheral surface of the outer end portion of the edge is allowed to abut on the outer peripheral rim of the speaker frame to perform the positioning of the edge, the positioning according to a gasket is unnecessary, and then the number of parts can be reduced.
According to the second aspect, in addition to the above function, a size of the speaker frame can be set largely by making the best use of a speaker setting area on a baffle plate or the other housing since the attaching screw section is provided inside the outer peripheral rim of the speaker frame. Further, the inside area of the speaker frame can be effectively utilized as the oscillation area.
Also, since the outer end portion formed at the outer end of the edge has a wall thickness thicker than the screw head of the attaching screw section, and the notch formed for avoiding the attaching screw section, the attaching screw can be prevented from exerting influence to the oscillation of the edge. In addition, according to the desired wall thickness of the outer end portion of the edge, the outer end portion can be bonded onto the attaching surface of the speaker frame, so that the same airtightness as one of gasket can be secured.